Return-Path: Received: from fieldses.org ([173.255.197.46]:36398 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932968AbdELQVQ (ORCPT ); Fri, 12 May 2017 12:21:16 -0400 Date: Fri, 12 May 2017 12:21:15 -0400 From: "J. Bruce Fields" To: NeilBrown Cc: Jan Kara , Jeff Layton , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [RFC PATCH v1 00/30] fs: inode->i_version rework and optimization Message-ID: <20170512162115.GH7704@fieldses.org> References: <20170330064724.GA21542@quack2.suse.cz> <1490872308.2694.1.camel@redhat.com> <20170330161231.GA9824@fieldses.org> <1490898932.2667.1.camel@redhat.com> <20170404183138.GC14303@fieldses.org> <878tnfiq7v.fsf@notabene.neil.brown.name> <20170405080551.GC8899@quack2.suse.cz> <20170405181409.GC28681@fieldses.org> <20170511185942.GD25434@fieldses.org> <87r2zvkp9c.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <87r2zvkp9c.fsf@notabene.neil.brown.name> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, May 12, 2017 at 08:22:23AM +1000, NeilBrown wrote: > On Thu, May 11 2017, J. Bruce Fields wrote: > > +static inline u64 nfsd4_change_attribute(struct inode *inode) > > +{ > > + u64 chattr; > > + > > + chattr = inode->i_ctime.tv_sec << 30; > > + chattr += inode->i_ctime.tv_nsec; > > + chattr += inode->i_version; > > + return chattr; > > So if I chmod a file, all clients will need to flush the content from their cache? > Maybe they already do? Maybe it is a boring corner case? Yeah, that's the assumption, maybe it's wrong. I can't recall complaints about anyone bitten by that case. > > /* > > * Fill in the pre_op attr for the wcc data > > */ > > @@ -253,7 +263,7 @@ fill_pre_wcc(struct svc_fh *fhp) > > fhp->fh_pre_mtime = inode->i_mtime; > > fhp->fh_pre_ctime = inode->i_ctime; > > fhp->fh_pre_size = inode->i_size; > > - fhp->fh_pre_change = inode->i_version; > > + fhp->fh_pre_change = nfsd4_change_attribute(inode); > > fhp->fh_pre_saved = true; > > } > > } > > --- a/fs/nfsd/nfs3xdr.c > > +++ b/fs/nfsd/nfs3xdr.c > > @@ -260,7 +260,7 @@ void fill_post_wcc(struct svc_fh *fhp) > > printk("nfsd: inode locked twice during operation.\n"); > > > > err = fh_getattr(fhp, &fhp->fh_post_attr); > > - fhp->fh_post_change = d_inode(fhp->fh_dentry)->i_version; > > + fhp->fh_post_change = nfsd4_change_attribute(d_inode(fhp->fh_dentry)); > > if (err) { > > fhp->fh_post_saved = false; > > /* Grab the ctime anyway - set_change_info might use it */ > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > > index 26780d53a6f9..a09532d4a383 100644 > > --- a/fs/nfsd/nfs4xdr.c > > +++ b/fs/nfsd/nfs4xdr.c > > @@ -1973,7 +1973,7 @@ static __be32 *encode_change(__be32 *p, struct kstat *stat, struct inode *inode, > > *p++ = cpu_to_be32(convert_to_wallclock(exp->cd->flush_time)); > > *p++ = 0; > > } else if (IS_I_VERSION(inode)) { > > - p = xdr_encode_hyper(p, inode->i_version); > > + p = xdr_encode_hyper(p, nfsd4_change_attribute(inode)); > > } else { > > *p++ = cpu_to_be32(stat->ctime.tv_sec); > > *p++ = cpu_to_be32(stat->ctime.tv_nsec); > > It is *really* confusing to find that fh_post_change is only set in nfs3 > code, and only used in nfs4 code. Yup. > It is probably time to get a 'version' field in 'struct kstat'. The pre/post_wcc code doesn't seem to be doing an explicit stat, I wonder if that matters? --b. > That would allow this code to get a little cleaner. > > (to me, this exercise is just a reminder that the NFSv4 change attribute > is poorly designed ... so it just makes me grumpy). > > NeilBrown > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html